The present invention generally relates to devices and methods for water treatment, particularly for use in a post-mix beverage dispenser.
The on-premises water treatment system and method described in U.S. Pat. No. 5,858,248 to Plester et al. utilizes a removable, disposable cartridge that includes a collector and a filter. The collector is disclosed to have a mesh structure. A heater heats water in the cartridge into order to breakdown bicarbonate hardness in the water. Precipitated carbonates and heavy metals are then deposited and collected on the surface of the mesh structure. Water from the collector then passes through a polishing filter, e.g., a ring filter, and exits the cartridge.
The effectiveness of the collector depends, in part, on control of the temperature and residence time of the water passing through the cartridge. In operation, the residence time decreases as the deposits accumulate and fill voids in the mesh structure. This accumulation process eventually causes the residence time to decrease below that needed to complete the precipitation process. The cartridge therefore is designed for the polishing filter to have a shorter useful life than the collector; a blocked filter signals the need for collector maintenance (i.e. replacement). It would advantageous to have an improved particle collection cartridge, particularly one designed to satisfy the following parameters:
A. To ensure that all parts of water flowing passing through the cartridge are treated to the same extent, the cartridge should provide a narrow distribution of in-cartridge residence time within the water flow;
B. The cartridge should provide efficient settling and collection of small particles formed during the heat induced reaction within the cartridge;
C. Blockage of the water inlet to the cartridge should be avoided by minimizing the deposition of particles forming, due to the heat induced reaction, just inside the water entry point to the cartridge;
D. Particle deposition on the heater surfaces of the cartridge also should be avoided, since such formation is detrimental to performance of the heater and cartridge;
E. The cartridge should provide complete separation of inlet and outlet water flow, so that leaks in the system cannot result in the mixing of the incoming untreated water with the outgoing treated water;
F. The cartridge should accommodate a polishing filter for the treated outgoing water, to remove any fine particles which carry over from the settling zones of the cartridge;
G. The cartridge should accommodate either an internally-mounted heater or an externally-mounted heater;
H. The cartridge should inherently block water flow through the cartridge when cartridge""s free internal space has been reduced by reaction particle deposition to an extent that the residence time of the water within the cartridge has reached a lowest limiting value, that is when the cartridge is xe2x80x9cspentxe2x80x9d and must be replaced;
I. The cartridge should provide good thermal contact with a heater mounted outside the cartridge, for those embodiments where such externally-mounted heaters are preferred;
J. The cartridge should provide water contact surfaces that can be effectively and economically lacquered to prevent metal contamination of treated water, particularly for embodiments using inexpensive metals such as mild steel;
K. The cartridge should provide lacquered heating surfaces that avoid deposits, so as to avoid subjecting the lacquer surfaces to unacceptable thermal stress; and
L. The cartridge should be a simple construction, of low cost, thereby enabling the cartridge to be a relatively inexpensive part of the water treatment system.
It would therefore be advantageous to develop a water treatment cartridge that minimizes the deposition of particles forming just inside the water entry point to the cartridge, that avoids particle deposition on the heater surfaces of the cartridge, and that provides complete separation of inlet and outlet water flow to and from the cartridge. It would furthermore be advantageous for such a cartridge to accommodate either an internally-mounted heater or an externally-mounted heater, wherein the cartridge inherently blocks water flow therethrough when the cartridge""s free internal space has been reduced by reaction particle deposition to an extent that the residence time of the water within the cartridge has reached a lowest limiting value, and wherein the water contact surfaces of the cartridge can be effectively and economically lacquered.
It is therefore an object of the present invention to provide a cartridge device for use in a heated cartridge water treatment system which meets many or all of these design parameters.
It is another object of the present invention to provide methods and water treatment systems which utilize such improved cartridge devices.
An improved cartridge device is provided for use in a water treatment system, such as the system described in U.S. Pat. No. 5,858,248. The cartridge includes multiple containers that are nested together and which form particle settling zones and channels for the flow of water within gaps between the walls of the containers. The cartridge is cost effective because it utilizes conventional, mass-produced parts and only simple assembly is needed.
In a preferred embodiment, the cartridge device includes (i) an outer container having a closed base, an open top end, and vertical walls disposed between the base and the top end, wherein the open top end can be sealably engaged with a headpiece of the heated cartridge water treatment system; (ii) an inner container having a closed base, a top end having at least one opening through which water to be treated can flow into the inner container, and vertical walls disposed between the base and the top end, wherein the vertical walls of the inner container are provided with at least one aperture through which water in the inner container can flow out of the inner container, a particle settling zone being defined between the aperture and the base of the inner container, and wherein the inner container is secured within the outer container in a position forming a gap between the walls of the outer container and the walls of the inner container and a gap between the base of the outer container and the base of the inner container; (iii) a first intermediate container disposed within a second intermediate container, disposed between the outer container and the inner container, wherein the intermediate containers have a closed base, an open top end, and vertical walls disposed between the base ends and the top ends, wherein water in the water flow path flows over the top end of the first intermediate container and then through apertures in the walls of the second intermediate container; and (iv) a treated water outlet positioned for receiving water from the gap between the top end of the outer container and the top end of the inner container. The containers forming the cartridge preferably are made of a metal, and can be lacquered to prevent metal contamination of the treated water. In this embodiment, the cartridge enables a heater for the treatment system to be optionally installed within the treated water flow or against an outer cartridge wall. A polishing filter, such as a depth filter, preferably is provided with the cartridge.
The cartridge includes a section for non-turbulent flow for the collection of particles formed inside the cartridge by the reaction of bicarbonates in the water, thus providing efficient particle collection. When the particle collecting section becomes full, the water flow automatically is blocked, or cut-off, which signals the need to replace the cartridge. In preferred embodiments where 50% of the water flow path is in the same direction as the settling direction of the particles, settling is also more effective.
In a more preferred embodiment, the cartridge device includes (i) an outer container having a closed base, an open top end, and vertical walls disposed between the base and top end, wherein the open top end can be sealably engaged with a headpiece of a heated cartridge water treatment system; (ii) an inner container having a closed base, an open top end, and vertical walls disposed between the base and top end, wherein the inner container is secured within the outer container in a position forming a gap between the walls of the outer and inner containers and a gap between the bases of the inner and outer containers, such that a particle settling zone is defined between said bases; (iii) one or more outer baffles secured in the gap between the walls of the outer container and inner containers, and defining a flow path such that when untreated water enters the cartridge through an inlet feedpipe, the water flows between the wall of the outer container and at least one of the outer baffles toward the particle settling zone and then passes between the outer baffle and the wall of the inner container; and (iv) a treated water outlet positioned for receiving water from the top end of the inner container, wherein water flowing out of the inner container flows through the treated water outlet and out of the cartridge device, thereby defining a water flow path through the cartridge device.